A Phylogenetic and Biogeographic Study of the Genus Lilaeopsis (Apiaceae Tribe Oenantheae) Author(S) :Tiffany S
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A Phylogenetic and Biogeographic Study of the Genus Lilaeopsis (Apiaceae Tribe Oenantheae) Author(s) :Tiffany S. Bone, Stephen R. Downie, James M. Affolter, and Krzysztof Spalik Source: Systematic Botany, 36(3):789-805. 2011. Published By: The American Society of Plant Taxonomists URL: http://www.bioone.org/doi/full/10.1600/036364411X583745 BioOne (www.bioone.org) is a a nonprofit, online aggregation of core research in the biological, ecological, and environmental sciences. BioOne provides a sustainable online platform for over 170 journals and books published by nonprofit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Web site, and all posted and associated content indicates your acceptance of BioOne’s Terms of Use, available at www.bioone.org/page/terms_of_use. Usage of BioOne content is strictly limited to personal, educational, and non-commercial use. Commercial inquiries or rights and permissions requests should be directed to the individual publisher as copyright holder. BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research. Systematic Botany (2011), 36(3): pp. 789–805 © Copyright 2011 by the American Society of Plant Taxonomists DOI 10.1600/036364411X583745 A Phylogenetic and Biogeographic Study of the Genus Lilaeopsis (Apiaceae tribe Oenantheae) Tiffany S. Bone , 1,4 Stephen R. Downie ,1, 5 James M. Affolter , 2 and Krzysztof Spalik 3 1 Department of Plant Biology, University of Illinois at Urbana-Champaign, Illinois 61801 U. S. A. 2 College of Agricultural and Environmental Sciences, University of Georgia, Athens, Georgia 30605 U.S.A. 3 Department of Plant Systematics and Geography, Faculty of Biology, University of Warsaw, Warsaw, Poland. 4 Present address: USDA, NCAUR, BFPM, 1815 North University, Office 3133, Peoria, Illinois 61604 U. S. A. 5 Author for correspondence ([email protected]) Communicating Editor: Allan J. Bornstein Abstract— The genus Lilaeopsis (Apiaceae subfamily Apioideae) comprises 15 species and exhibits both American amphitropic and amphi- antarctic patterns of disjunction. The group is difficult taxonomically because of its simplified habit, phenotypic plasticity of vegetative charac- ters, and extensive variation in fruit characters. Sequence data from the nrDNA ITS and cpDNA rps16 intron and rps16-trnK intergenic spacer regions were obtained for 60 accessions, representing 13 species of Lilaeopsis and five closely related outgroup genera from the North American Endemics clade of tribe Oenantheae. These molecular data were subjected to maximum parsimony, Bayesian inference, and dispersal-vicariance analyses in an effort to reconstruct evolutionary relationships and infer biogeographic scenarios. The results suggest that: (1) L. macloviana , L. masonii , and L. occidentalis , distributed in western South America and western North America, collectively represent a single, polymorphic species of amphitropic distribution; (2) The Australasian species L. brisbanica, L. novae-zelandiae, L. polyantha , and L. ruthiana comprise a well- supported clade. However, L. novae-zelandiae is not monophyletic, but may be rendered so by the inclusion of all Australasian taxa into one polymorphic species; (3) L. mauritiana from Mauritius is closely related to L. brasiliensis from South America and may even be subsumed under the latter pending further investigation; and (4) Lilaeopsis probably originated in South America following a dispersal of its ancestor from North America. A minimum of seven dispersal events is necessary to explain its present-day distribution, including one dispersal from South America to Australia or New Zealand, two dispersals between Australia and New Zealand, and three dispersals from South America to North America. Keywords— Amphitropic disjunction , Apioideae , cpDNA , ITS , phylogeny. The genus Lilaeopsis Greene (Apiaceae subfamily Apioideae) nized by Hill (1928) were consolidated within the single poly- consists of small, creeping, rhizomatous, perennial herbs morphic taxon L. novae-zelandiae ; and three additional species occupying damp, marshy, or truly aquatic habitats, with fif- from Australia were interpreted as intergrading forms of teen species and four infraspecific taxa currently recognized L. polyantha . In general, vegetative characters were deemed of ( Table 1 ). The group is difficult taxonomically because the little value for distinguishing among species, and fruit char- plants have a simplified and generally similar vegetative acters of the three polymorphic species were observed to be morphology. In all species the leaves are linear, hollow, and extremely variable, sometimes showing overlapping varia- transversely septate, being derived from the rachis-axis of a tion between species. To confound matters, specimens are compound leaf, with the septae corresponding to the posi- often impossible to identify to species without mature fruits, tions of pinnae insertion in pinnatifid leaves ( Kaplan 1970 ; so in some instances geography must be used to circumscribe Charlton 1992 ). These rachis leaves are different from those them. As stated by Affolter (1985) , “Morphological simplifi- typical of other umbellifers (such as carrot, dill, parsnip, and cation has reduced the number of characters available to the celery) where they are generally pinnately compound and taxonomist; phenotypic plasticity has diminished the utility dissected. of the few characters which remain.” Further consolidation The taxonomic history of Lilaeopsis is detailed by Affolter of species was also considered by Affolter (1985) , but “would (1985) and underscores the problems in classifying plants carry the process a step too far and would obscure real dif- having a reduced vegetative morphology. Affinities to both ferences that exist among the South American, New Zealand, Araliaceae (i.e. Hydrocotyle L.) and Apiaceae have been pro- and Australian populations.” posed, with the phylogenetic position and monophyly of Molecular systematic studies indicate that Lilaeopsis is a Lilaeopsis only confirmed recently ( Downie et al. 2000 , 2001 , member of Apiaceae tribe Oenantheae ( Downie et al. 2000 ). 2008 ; Petersen et al. 2002 ). Through extensive field inves- While no unique morphological synapomorphy supports the tigations, cultivation of living material of most species in a monophyly of Oenantheae ( Petersen et al. 2002 ), the plants do common-garden coupled with the growth of many collec- share certain traits, such as glabrous stems and leaves, clus- tions under different environmental treatments, and sta- ters of fibrous or tuberous-thickened roots, globose to broadly tistical analyses, Affolter (1985) showed that the shape and ovate spongy-thickened fruits, and a preference for wet habi- size of the rachis leaves of Lilaeopsis are readily modified in tats ( Downie et al. 2008 ). The “spongy cells” within the fruits response to various degrees of submergence and light inten- are storage tracheids, nearly isodiametric in form and bigger sity. Fruit characters, so important in umbellifer classifica- in diameter than typical tracheids. They enhance buoyancy tion, continued to receive emphasis, but recognition of their and facilitate dispersal in aquatic environments when the extensive variation in some taxa resulted in merging many fruits dry out and these cells become filled with air ( Briquet previously recognized species. As examples, six previously 1897 ; Hill 1927 ; Affolter 1985 ). Like Lilaeopsis , some plants of described species and several infraspecific taxa were consol- the tribe possess rachis or rachis-like leaves, such as Oxypolis idated within the single polymorphic species L. macloviana Raf., Ptilimnium Raf., Cynosciadium DC., and Limnosciadium from South America; the three New Zealand species recog- Mathias & Constance. The genus Lilaeopsis is unequivocally 789 790 SYSTEMATIC BOTANY [Volume 36 Table 1. Lilaeopsis taxa and their geographic distributions (after of Lilaeopsis have also been collected from the Kerguelen Affolter 1985 , Bean 1997 , and Petersen and Affolter 1999 ). Asterisks denote Archipelago ( Affolter 1985 ). taxa not included in the molecular analysis. Both northern and southern hemispheric origins for Taxon Distribution Lilaeopsis have been suggested. Dawson (1971) , for example, indicated that Lilaeopsis probably originated in the northern L. attenuata (Hook. & Arn.) Fern. Argentina subsp. attenuata hemisphere, whereas Hill (1929) postulated an Antarctic ori- L. attenuata subsp. ulei (Pérez-Mor.) Brazil gin, with two major subsequent migration routes northward Affolter* (one route leading to New Zealand and Australia, and the L. brasiliensis (Glaz.) Affolter Argentina, Brazil, Paraguay other leading into and through the Andes of South America L. brisbanica A. R. Bean Australia into North America). Raynal (1977) described Lilaeopsis as a L. carolinensis J. M. Coult. & Rose U. S. A. (Atlantic and Gulf coasts) “genuinely Gondwanian genus.” The southern hemisphere South America (Argentina, Brazil, Paraguay, Uruguay) has traditionally been considered to exhibit a vicariant his- Europe (Portugal, Spain) tory, with the fragmentation of Gondwana leading to the L. chinensis (L.) Kuntze Canada and U. S. A. (Atlantic and division of its ancestral biota ( Sanmartín and Ronquist 2004 ). Gulf coasts) However, recent biogeographic